Abstract:

Primary cutaneous lymphocytic proliferations showing T follicular helper (TFH) phenotype comprise CD4+ small medium T cell lymphoproliferative disorder (CD4+SMLPD) and rare examples of mycosis fungoides (MF) and CD30+ T cell LPD. Systemic TFH lymphomas such as angioimmunoblastic T-cell lymphoma (AITL) may also involve the skin. However, primary cutaneous lesions showing TFH phenotype and lacking the typical clinicopathological features of CD4+SMLPD, MF, or AITL are rarely encountered. Thirty-four skin biopsies from 11 patients were studied, including 6 men and 5 women (median age: 64.5 [28-80y]) with 33 months of median follow-up. Patients presented with multiple violaceous papulonodules and/or plaques on face, trunk, and extremities. Six patients had stable disease or regression of the lesions, while 5 progressed with lymph node and/or blood involvement. Three patients died of disease (median survival: 33 months). History of immune dysregulation was noted in 3 patients (autoimmune disease and previous immunotherapy for cancer). Histopathological findings included: dermal infiltrate (diffuse, nodular to perivascular and periadnexal) of small to medium-sized atypical lymphocytes with scattered large cells; absence of marked epidermotropism; frequent admixture of B-cells, histiocytes, plasma cells, and eosinophils. The infiltrate showed predominance of CD4 expression; partial loss of CD7 (10/11); with at least two TFH markers (PD1, CXCL13, ICOS, BCL6, CD10); occasional CD30 positivity and lack of Epstein-Barr virus association. Clonal TCR rearrangements were detected (10/11). Primary cutaneous TFH lymphomas/LPD may constitute a separate group of diseases with clinical presentations not typical of MF, CD4+SMLPD, or other entities included in the current WHO classification, and appear to show a spectrum of outcomes. Recognition of TFH phenotype in these processes is important for accurate diagnosis and management.

Financial Disclosure:
No current or relevant financial relationships exist.

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Ziba Rahbar, MD, MPH